1. Field of the Invention
The present invention relates to a moving object with at least two energy output sources including fuel cells incorporated therein, a driving apparatus for the moving object, and a method of controlling the moving object.
2. Description of the Related Art
Hybrid vehicles with an engine and a motor mounted thereon have been proposed recently. In one form of the hybrid vehicle called a parallel hybrid vehicle, the power of both the motor and the engine is output to a drive shaft. The parallel hybrid vehicle has the engine and a battery as energy output sources to produce mechanical and electrical power to rotate the drive shaft. The parallel hybrid vehicle may run only with the power from the engine or from the battery. Proper conditional use of these two energy output sources enables the engine to operate in an efficient operating range. The motor may also act as a generator to convert the mechanical power of the driving shaft into electric power while causing a braking force to the driving shaft. The regenerative braking by the motor recovers the kinetic energy of the vehicle to charge the battery. Because of these functions, the parallel hybrid vehicle has excellent fuel consumption and environmental properties.
Another form of the hybrid vehicle is called a series hybrid vehicle. The series hybrid vehicle runs with power from a motor connected with the drive shaft. The engine is disposed separately from the drive shaft and drives a generator to generate electric power. The motor is driven by either the electric power generated by the generator or the electric power supplied from a battery. The series hybrid vehicle also has the two energy output sources of the engine and the battery. Proper combinational use of these two energy output sources ensures the excellent fuel consumption and environmental properties.
Some vehicles with fuel cells mounted thereon as one of energy output sources have been proposed as one type of the parallel hybrid vehicle (for example, a vehicle disclosed in JAPANESE PATENT LAID-OPEN GAZETTE No. 3-148330). The fuel cells oxidize hydrogen, or fuel, to generate electric power. The exhaust from the fuel cells is water vapor and does not contain any harmful components. The fuel cells accordingly have extremely excellent environmental properties. Some types of fuel cells utilize a hydrogen rich gas generated by reforming of a fuel, such as methanol. Hybrid vehicles having these fuel cells and a gasoline engine are provided with a plurality of fuel reservoirs, in which methanol and gasoline are separately stored.
The fuel cell technology is being under rapid development these days. There is accordingly no sufficient discussion on the optimum combination of the output characteristics of the fuel cells with those of another energy output sources such as a heat engine. The fuel cells generate electrical energy like secondary batteries, but they are irreversible energy output sources. The secondary battery is rechargeable even in the course of a drive of the hybrid vehicle. The fuel cells, on the other hand, do not recover their power generation ability without an external supply of fuel. Another disadvantage of the fuel cells is a poor response.
Hybrid vehicles with the fuel cells have been proposed to combine the advantages of the conventionally used engine with these of the fuel cells. In the proposed hybrid vehicles with the fuel cells, however, the effective use of the fuel cells has not been fully considered by taking into account the above characteristics.
In the proposed hybrid vehicles with the fuel cells mounted thereon, the fuel cells are used only in a limited manner and not fully utilized. The favorable fuel consumption and the other advantages of the hybrid vehicle have not been fully utilized. Sufficient warming up is generally required in the process of power generation by the fuel cells. The fuel cells accordingly have a poor response to a requirement of power generation. There has been no sufficient discussion on the method of compensating for the poor response and outputting the required electric power.
In the proposed hybrid vehicles with the fuel cells mounted thereon, there has been substantially no discussion on the selective use of energy output sources at a drive in a specific condition that is different from a normal drive. There has also been substantially no discussion on the technique of utilizing the characteristics of the fuel cells as an electric power supply of high efficiency and excellent environmental properties, so as to improve the facility of the hybrid vehicle.
In the vehicle with a plurality of energy output sources requiring different types of fuels, such as fuel cells and a gasoline engine, it is required to supply the corresponding fuels to the respective fuel reservoirs or tanks without any confusion. No simple structure, however, has been proposed to prevent confusion between the plurality of fuels supplied.
The conventional vehicles have another problem relating to vibration damping of the engine as discussed below. The engine generally has a pulsation or variation in its output torque. In a vehicle with a motor in addition to the engine as a mechanism to output a torque to the drive shaft, the motor can compensate for a variation in the torque output from the engine to the drive shaft. There has been no sufficient discussion on the effective use of the fuel cells as the electric power supply of the motor in the torque control.
When the engine torque is greater than a required torque, the motor carries out regenerative operation to give a load, thereby attaining the required torque output. When the engine torque is less than the required torque, on the other hand, the motor carries out power operation to attain the required torque output. The torque control is generally accompanied by extraction and supply of electric power from and into the motor. The conventional technique implements such control with the secondary battery. The fuel cells are the power generator unit that carries out only power generation, and can not replace the secondary battery.
The torque control technique with the secondary battery, however, has a problem that the extraction and supply of electric power from and into the motor are difficult to balance, and thereby the electric power of the secondary battery is often consumed excessively. This is ascribed to a conversion loss between the mechanical power and the electric power due to the charge and discharge efficiencies of the secondary battery.
One proposed technique for compensating the conversion loss includes the use of another electric power supply. The fuel cells may be used as such an electric power supply for compensation. While the motor carries out power operation for the vibration damping, this proposed technique restricts the discharge of the secondary battery by the amount of the electric power previously regenerated and causes the fuel cells to compensate for an insufficiency of electric power. The electric power supplied from the secondary battery, however, has a low efficiency due to the losses in the charging and discharging process. The primary use of such electric power results in lowering the energy efficiency in the vibration damping. The use of the fuel cells for the purpose of compensation does not effectively draw the advantages of the fuel cells having the high efficiency of power generation.
The issues discussed above arise not only in the hybrid vehicles but in any moving objects having a plurality of energy output sources including fuel cells.
One object of the present invention is thus to provide a moving object with fuel cells mounted thereon, which effectively uses the fuel cells as an energy output source and has excellent fuel consumption and environmental properties.
Another object of the present invention is to provide a simple structure that effectively prevents confusion between a plurality of fuels supplied.
Still another object of the present invention is to provide a technique that efficiently controls a variation in torque output from a heat engine with a torque of a motor.
At least part of the above and other related objects is actualized by a first moving object having at least two energy output sources including a fuel cell. The first moving object includes: a detector that measures at least either one of an output sustaining ability and a variation thereof with regard to at least one of the at least two energy output sources; and an output controller that controls an output state of energy from each of the at least two energy output sources, based on a result of the measurement by the detector, so as to ensure output of a required total energy.
The first moving object of the present invention has at least two energy output sources including fuel cells. The energy output source outputs energy in a variety of forms including mechanical energy and electrical energy. The fuel cells are the energy output source that outputs electrical energy. It is not necessary that the at least two energy output sources output different forms of energy. The at least two energy output sources may, however, output the same form of energy as in the case of the fuel cells and a secondary battery.
The first moving object of the present invention controls the output state of each of the plural energy output sources according to its output sustaining ability. For example, the fuel cells can be controlled to have the output according to at least either one of the output sustaining ability and the variation thereof. The output sustaining ability here means a total quantity of energy that can be output continuously from each energy output source. The output sustaining ability of the fuel cells is defined, for example, as the ability of the fuel cells for continuously performing the power generation and corresponds to a physical quantity obtained as a time integral of the electric power that can be output from the fuel cells. Even if the energy output source can output the required electric power, in the case where the required level of electric power is kept only for a short time period, it is determined that the energy output source has a low output sustaining ability.
The continuous output of high energy from the fuel cells having the low output sustaining ability may cause the fuel cells to fall into a power generation-unable state. The fuel cells in this state can no longer be used as the energy output source. In this case, the moving object should be driven with the energy output source or sources other than the fuel cells. The moving object with a plurality of energy output sources mounted thereon attains a drive of high efficiency by properly using these energy output sources. If the fuel cells can not be used as one of the energy output sources, there is an undesirable restriction in use of the energy output sources. This lowers the driving efficiency. Controlling the output of the fuel cells according to the output sustaining ability enables the fuel cells to be kept in the power generation-capable state over a long time period. The variation in output sustaining ability is regarded as a parameter indirectly representing the future output sustaining ability. The control may thus be carried out according to the variation in output sustaining ability, in order to keep the fuel cells in the power generation-capable state over a long time period. The control may alternatively be performed according to both the output sustaining ability and its variation. The first moving object of the present invention controls the output of the fuel cells in this manner and thus ensures the proper use of the respective energy output sources during a long drive. This desirably improves the driving efficiency and the environmental properties. In other words, the first moving object of the present invention adequately reduces the consumption of the FC fuel, in order to allow the fuel cells to be used in the specific conditions that effectively utilize the power generation ability of the fuel cells, thereby improving the driving efficiency and the environmental properties. The above description regards the control of the output of the fuel cells. The principle of the present invention, however, enables the proper use of the energy output sources according to the observed output sustaining ability of any other energy output source.
In the moving object, the operation of each constituent is generally controlled by taking into account the energy per unit time. The term xe2x80x98energyxe2x80x99 used in the specification hereof means the energy per unit time, unless otherwise specified. In this specification, the term xe2x80x98energyxe2x80x99 is synonymous, in principle, with the terms xe2x80x98powerxe2x80x99 and xe2x80x98electric powerxe2x80x99.
The term xe2x80x98moving objectxe2x80x99 used in the specification hereof includes a diversity of moving objects that move with the power, for example, vehicles, ships and vessels, aircraft, airships, and other flying objects. The purpose of the moving object is not restricted to the transportation of people or things nor to the boarding.
In accordance with one preferable application of the first moving object, the detector measures at least either one of the output sustaining ability of the fuel cell and the variation thereof, based on a remaining quantity of a fuel for the fuel cell.
This application enables the output sustaining ability and the variation thereof to be securely measured by the simplest procedure. The fuel cells are an irreversible energy output source that can not perform power generation without an external supply of a fuel once the fuel for the fuel cells (hereinafter referred to as the FC fuel) has been used up. Measurement of the output sustaining ability using the remaining quantity of the FC fuel as the parameter enables the irreversibility of the fuel cells to be evaluated in the most appropriate manner. This ensures the proper control by taking into account the characteristics of the fuel cells. In the case where the variation of the output sustaining ability is observed, it is not necessary to measure the absolute value of the remaining quantity of the FC fuel, but only a variation in remaining quantity of the FC fuel may be measured. Similarly, in the case where a heat engine is used as one of the energy output sources, the output sustaining ability of the heat engine may be measured, based on the remaining quantity of a fuel supplied to the heat engine.
In accordance with another preferable application of the first moving object, the detector measures at least either one of the output sustaining ability of the fuel cell and the variation thereof, based on a loading state of the fuel cell. The loading state is defined, for example, by the electric power output from the fuel cells or the output of the motor driven by the fuel cells as the parameter. The output sustaining ability of the fuel cells varies with a variation in loading applied to the fuel cells. The continuous monitor of the loading state allows measurement of the output sustaining ability or its variation. Similarly, in the case where a heat engine is used as one of the energy output sources, the output sustaining ability of the heat engine may be measured, based on the loading state of the heat engine.
The output sustaining ability and its variation may be defined by a variety of other parameters. For example, the temperature of the fuel cells may be used for the measurement. When the temperature of the fuel cells is abnormally high, it is required to interrupt the power generation, in order to lower the temperature. The abnormally high temperature can thus be regarded as the case of the lowered output sustaining ability. When the temperature of the fuel cells does not sufficiently rise to the allowable level for power generation, this is also regarded as the case of the lowered output sustaining ability. In the case where the temperature of the fuel cells is used as the parameter, it may be determined that the output sustaining ability is improved according to a temperature variation subsequent to the determination of the lowered output sustaining ability. In another example, the output sustaining ability may be evaluated, based on the determination of whether the fuel cells function properly or malfunction.
In the first moving object of the present invention, the at least two energy output sources may include the fuel cell and a heat engine.
The fuel cells are the output source of electrical energy, whereas the heat engine is the output source of mechanical energy. The use of the two different energy output sources that respectively output different forms of energy ensures the mutual supplement in the areas of low driving efficiency, thereby attaining a drive of high efficiency as a whole. The available energy output sources are, however, not restricted to these two examples.
In accordance with one preferable embodiment of the moving object that has the fuel cells and the heat engine as the energy output sources, the detector measures at least either one of the output sustaining ability of the heat engine and the variation thereof. The output controller selects the fuel cell to be used in place of the heat engine as a working energy output source even in a specific driving range where the heat engine is to be used as the working energy output source, when the observed output sustaining ability of the heat engine is lower than a predetermined level.
In the case of the lowered output sustaining ability of the heat engine, the change of the working energy output source from the heat engine to the fuel cells effectively restricts the use of the heat engine and desirably prevents a further decrease in output sustaining ability. This enables the heat engine to be kept in a workable state, and ensures the proper use of the fuel cells and the heat engine in other driving conditions. The predetermined level used as the criterion for the control is arbitrarily set and may vary according to the driving state of the moving object. The control may be performed at a time point when the observed output sustaining ability is actually lower than the predetermined level or at a time point when the output sustaining ability is expected to be lower than the predetermined level.
As discussed above, the principle of the present invention is applicable to the diversity of moving objects having the various energy output sources. The control of the fuel cells may be implemented by a variety of techniques. The following describes some applications of the control procedure.
In accordance with one preferable application of the present invention, the first moving object further includes: a drive shaft that outputs power; and a mechanical energy output mechanism that converts energy output from each of the at least two energy output sources into mechanical energy and outputs the converted mechanical energy to the drive shaft. The required total energy is expressed as a quantity of mechanical energy output from the drive shaft per unit time.
This application carries out the control based on the mechanical energy output to the drive shaft. In the case of the energy output source outputting the electrical energy, such as the fuel cells, a motor may correspond to the mechanical energy output mechanism. In the case of the energy output source outputting the mechanical energy, such as the heat engine, a mechanism for transmitting the output energy to the drive shaft may correspond to the mechanical energy output mechanism. In this case, the output shaft of the heat engine may be linked directly with the drive shaft. In the first moving object of the above application, the output of the fuel cells is regulated according to at least either one of the output sustaining ability and its variation. This technique enables the power to be output from the drive shaft while properly using the respective energy output sources. This output power is mainly used to move the moving object. This structure accordingly ensures a highly efficient movement of the moving object.
In accordance with one preferable application of the moving object that controls the power output from the drive shaft, the output controller narrows a preset driving range of the moving object, in which a predetermined energy output source selected out of the at least two energy output sources is mainly used to output the required total energy, with a decrease in output sustaining ability of the selected energy output source.
For example, in the case where the predetermined energy output source is the fuel cells, the output controller narrows the preset driving range of the moving object, in which the fuel cells are mainly used to output the required total energy, with a decrease in output sustaining ability of the fuel cells.
In the first moving object of this application, the preset driving range, in which the fuel cells are mainly used, is narrowed with a decrease in output sustaining ability of the fuel cells. This reduces the frequency of consumption of the FC fuel. The driving range here is defined, for example, by the driving force required for the movement and the moving velocity as the parameters. The narrowed driving range of the moving object reduces the consumption of the FC fuel. The preset driving range of the moving object may be narrowed in a stepwise manner or continuously with a decrease in output sustaining ability of the fuel cells. The similar control procedure may be applied for any energy output source other than the fuel cells.
In accordance with another preferable application of the moving object that controls the power output from the drive shaft, the output controller reduces a torque, which is to be output by utilizing a predetermined energy output source selected out of the at least two energy output sources, with a decrease in output sustaining ability of the selected energy output source. For example, in the case where the predetermined energy output source is the fuel cells, the output torque by utilizing the fuel cells is reduced with a decrease in output sustaining ability of the fuel cells. This arrangement effectively reduces the loading of the selected energy output source, for example, the fuel cells. This prevents a further decrease in output sustaining ability of the fuel cells and thereby desirably reduces the consumption of the FC fuel.
In accordance with a concrete embodiment of the moving object that controls the power output from the drive shaft, the at least two energy output sources include a heat engine, the fuel cell, and a secondary battery. The mechanical energy output mechanism includes at least a motor that is rotatable with electric power output from the fuel cell and the secondary battery. The output controller varies at least either one of a driving area of the motor and an output torque of the motor in a specific driving range of the moving object, based on an output sustaining ability of the fuel cell.
The first moving object of this arrangement varies at least either one of the driving area of the motor and the output torque of the motor, so as to reduce the consumption of the FC fuel based on the functions discussed previously. The moving object has the secondary battery as the electric power supply for driving the motor. This enables the insufficiency of electric power due to the decreased loading of the fuel cells to be compensated with the electric power output from the secondary battery, thus ensuring the proper use of the respective energy output sources with a high degree of freedom. This technique desirably reduces the loading of the fuel cells without damaging the ride of the moving object or the response.
In accordance with another preferable application of the present invention, the first moving object further includes: an accumulator that is charged with electric power and is discharged to release electric power; and an electrical energy output mechanism that converts energy output from each of the at least two energy output sources into electrical energy, which is supplied to charge the accumulator. The required total energy is expressed as a quantity of electrical energy required to increase a charge level of the accumulator to a predetermined degree.
This application carries out the control based on the electrical energy supplied to charge the accumulator. The electric power accumulated in the accumulator, such as a secondary battery or a capacitor, may be used to drive the moving object via a motor or to drive a diversity of auxiliary machines. In the case of the energy output source outputting the electrical energy, such as the fuel cells, a conductor, through which the output electric power is transmitted, may correspond to the electrical energy output mechanism. In the case of the energy output source outputting the mechanical energy, such as the heat engine, a generator driven with the mechanical energy may correspond to the electrical energy output mechanism. The technique of the above application controls the output of the fuel cells according to the output sustaining ability, thereby enabling the charging control of the accumulator with the proper use of the respective energy output sources.
In accordance with one preferable embodiment of the moving object that carries out the charging control of the accumulator, the output controller lowers the predetermined degree, which is set as a target charge level of the accumulator, with a decrease in output sustaining ability of a specific energy output source that mainly outputs electric power to charge the accumulator.
Lowering the predetermined degree, which is the target level of the electric power to be accumulated in the accumulator, naturally decreases the total electric power to be output from the energy output sources to the accumulator. This accordingly decreases the electric power to be output from the fuel cells. The first moving object of this arrangement lowers the target level of the electric power to be accumulated in the accumulator according to the output sustaining ability, thereby reducing the consumption of the FC fuel.
In accordance with another preferable embodiment of the moving object that carries out the charging control of the accumulator, the output controller reduces a ratio of an output of a specific energy output source, which mainly outputs electric power to charge the accumulator, to the total energy with a decrease in output sustaining ability of the specific energy output source.
This arrangement properly uses the energy output sources while keeping the target level of the electric power to be accumulated in the accumulator. With a decrease in output sustaining ability, the first moving object of this arrangement reduces the output of the fuel cells and compensates the insufficiency with the energy output from another energy output source, so as to charge the accumulator. The technique of this embodiment thus effectively reduces the consumption of the FC fuel.
In the case of lowering the output of the fuel cells, it is preferable that the output controller heightens the predetermined degree, which is set as a target charge level of the accumulator, with a decrease in output sustaining ability of a specific energy output source that mainly outputs electric power to charge the accumulator.
In the case where the output sustaining ability is lowered, it is preferable to reduce the output of the fuel cells in any state in addition to the charging state of the accumulator. From this point of view, it is favorable that the electric power accumulated in the accumulator is kept at a sufficiently high level. In the case of the lowered output sustaining ability, this arrangement reduces the output of the fuel cells and enables a large quantity of electric power to be accumulated in the accumulator using the output from another energy output source. This technique effectively reduces the consumption of the FC fuel under a variety of conditions requiring electric power.
A combination of the above two control techniques may be applied to the moving object that carries out the charging control. In the case of the lowered output sustaining ability, the combined arrangement lowers the predetermined degree set in the accumulator while reducing the ratio of the output of the fuel cells to the total energy. In any of the applications discussed above, the predetermined degree and the ratio of the output may be lowered with a decrease in output sustaining ability in a stepwise manner or continuously.
The first moving object of the present invention may carry out the control discussed above, based on the output sustaining ability. In the case where the detector measures a variation in output sustaining ability with regard to at least one of the at least two energy output sources, however, the output controller may vary an output of the at least one energy output source, with regard to which the variation in output sustaining ability is measured, at a speed corresponding to the observed variation. For example, in the case where the output sustaining ability abruptly decreases, the output of the fuel cells should abruptly be reduced with the abrupt decrease. This arrangement effectively prevents excessive consumption of the FC fuel. This control technique regulates the consumption of the FC fuel according to the variation in output sustaining ability in the course of a drive of the moving object. The output variation speed of the fuel cells may be varied continuously or in a stepwise manner according to the variation in output sustaining ability.
In accordance with one preferable embodiment of the moving object, the output controller changes a working energy output source according to a driving state of the moving object, so as to output the total energy. The output controller forbids a change of the working energy output source to a specific energy output source that is determined to have an output sustaining ability of not greater than a preset level. In a moving object with fuel cells and a heat engine mounted thereon, for example, when the remaining quantity of the fuel for the heat engine decreases to or below a predetermined level, the fuel cells should continuously be used as the working energy output source even in the specific driving state that generally recommends a change of the working energy output source from the fuel cells to the heat engine.
In accordance with another preferable embodiment of the moving object, the output controller changes a working energy output source according to a driving state of the moving object, so as to output the total energy. The output controller performs a change of the working energy output source from a specific energy output source, which is determined to have an output sustaining ability of not greater than a preset level, to another energy output source even if the driving state of the moving object recommends a selection of the specific energy output source as the working energy output source. In the moving object with the fuel cells and the heat engine mounted thereon, for example, when the remaining quantity of the fuel for the heat engine decreases to or below a predetermined level, the working energy output source should be changed from the heat engine to the fuel cells.
These arrangements effectively restrict the use of the specific energy output source having the lowered output sustaining ability. The continuous use of the specific energy output source in the state of low output sustaining ability results in lowering the driving efficiency and may further cause an abrupt change of the total output energy when the specific energy output source falls into an output-unable state. This may significantly damage the drive feeling of the moving object. These arrangements of the present invention favorably prevent the drive feeling from being abruptly changed.
In the latter arrangement that changes the working energy output source from the specific energy output source having the lowered output sustaining ability to another energy output source, it is preferable that each of the at least two energy output sources has a mechanism that outputs rotational power to a drive shaft of the moving object. The output controller performs the change of the working energy output source from the specific energy output source to the another energy output source in a specific driving state of the moving object, where a difference between torques said specific energy output sources can output is within a preset range.
This arrangement effectively restricts a variation in torque at the time of the change within the preset range and thereby reduces the potential shock. The preset range may arbitrarily be determined in an allowable area according to the type of the moving object.
In accordance with another preferable application of the present invention, the first moving object further includes a driving state input unit that inputs a predetermined parameter representing a driving state of the moving object. The output controller varies a reference value, which is used to control the output state of energy from each of the at least two energy output sources based on the result of the measurement, with a variation of the predetermined parameter.
This arrangement ensures the flexible use of the energy output sources according to the driving conditions and thereby actualizes a highly efficient drive suitable for the drive feeling. There are a variety of parameters usable as direct indexes of the driving conditions; for example, the moving velocity of the moving object and the accelerator travel indicating a required power. In the structure having a system that gives information on the course of the moving object, various pieces of information obtained from this system may also be used as the parameters.
Another embodiment of the present invention is a driving apparatus having a main part identical with that of the moving object discussed above.
The present invention is accordingly directed to a driving apparatus having at least two energy output sources including a fuel cell. The driving apparatus includes: an estimation unit that estimates at least either one of a remaining power and a variation thereof with regard to at least one of the at least two energy output sources; and an output distribution controller that regulates a distribution of total energy to be output from the at least two energy output sources among the at least two energy output sources, based on a result of the estimation by the estimation unit.
Because of the same functions as those discussed above with regard to the moving object, the driving apparatus of the present invention ensures a drive of high efficiency and excellent environmental properties.
The remaining power here corresponds to a physical quantity obtained as a time integral of the electric power output from each energy output source. The remaining power can be estimated with a variety of parameters.
For example, the estimation unit may estimate at least either one of the remaining power and the variation thereof with regard to the fuel cell, based on either one of a remaining quantity of a fuel for the fuel cell and a remaining quantity of a raw material used to produce the fuel for the fuel cell.
In accordance with one preferable embodiment of the driving apparatus, the output distribution controller regulates the distribution while allowing at least one energy output source other than the fuel cell to have a negative output energy.
Setting a negative value to the output energy means that the energy output source prepares for an input of energy. For example, in the case where a chargeable and dischargeable accumulator is used as one of the energy output sources, the state of negative output energy corresponds to charging state of the accumulator. Setting the negative value to the output energy enables the energy state of the energy output source in the driving apparatus preparing for an input of energy to be recovered with the energy output from the other energy output sources including the fuel cells.
Like the first moving object of the present invention discussed above, there are a variety of possible arrangements applicable for the driving apparatus.
In accordance with one preferable application of the driving apparatus, the output distribution controller changes a working energy output source according to a driving state of the driving apparatus, so as to output the total energy. The output distribution controller forbids a change of the working energy output source to a specific energy output source that is determined to have a remaining power of not greater than a preset level.
In accordance with another preferable application of the driving apparatus, the output distribution controller changes a working energy output source according to a driving state of the driving apparatus, so as to output the total energy. The output distribution controller performs a change of the working energy output source from a specific energy output source, which is determined to have a remaining power of not greater than a preset level, to another energy output source even if the driving state of the moving object recommends a selection of the specific energy output source as the working energy output source.
In this case, it is further preferable that the output distribution controller performs a change of the working energy output source from the specific energy output source to the another energy output source in a specific driving state of the driving apparatus, where a total torque output from both the specific energy output source and the another energy output source to the drive shaft of the driving apparatus is within a preset range.
In accordance with another preferable application of the present invention, the driving apparatus further includes a driving state input unit that inputs a predetermined parameter representing a driving state of the driving apparatus. The output distribution controller varies a reference value, which is used to regulate the distribution of the total energy to be output from the at least two energy output sources among the at least two energy output sources based on the result of the estimation by the estimation unit, with a variation of the predetermined parameter.
Because of the same functions as those discussed above with regard to the moving object, these arrangements ensure the efficient use of the respective energy output sources suitable for the drive feeling.
The present invention is also directed to a method of controlling a drive of a moving object that has at least two energy output sources including a fuel cell. The method includes the steps of: (a) measuring at least either one of an output sustaining ability and a variation thereof with regard to at least one of the at least two energy output sources; (b) setting a total energy to be output from the at least two energy output sources; and (c) regulating energy to be output from each of the at least two energy output sources based on a result of the measurement in the step (a) and controlling the each energy output source, so as to output the total energy set in the step (b).
Part of the objects mentioned above is also actualized by a second moving object having a motor and a heat engine as power sources. The second moving object includes: a fuel cell and a secondary battery as electric power supplies of the motor; a regulation unit that regulates supplies of electric power fed from the fuel cell and the secondary battery to the motor; and a control unit that controls operations of the electric power supplies and the power sources according to a driving state of the moving object.
The second moving object of the present invention includes fuel cells and a secondary battery as the electric power supplies. As described previously, the fuel cells are the highly efficient energy source having the excellent environmental properties. The fuel cells generate power through the oxidation reaction of a fuel and thereby have a disadvantage that the sufficient power generation can not be performed once the fuel has been used up. Another disadvantage of the fuel cells is a time lag before the reaction proceeds to start power generation. The secondary battery is, on the other hand, a reversible energy source that can recover the level of electric power by charging even after the total consumption of electric power. The advantage of the secondary battery is a quick supply of electric power without any delay.
The second moving object of the present invention has the two electric power supplies having different characteristics. The control unit works to properly use these two electric power supplies, thereby attaining a favorable drive of the moving object that effectively utilizes the advantages of the respective electric power supplies. In the moving object with only the fuel cells mounted thereon as the electric power supply, the motor can no longer be used as the power source after the fuel for the fuel cells has been used up. The second moving object of the present invention, on the other hand, has the two different electric power supplies mounted thereon. The proper use of these two electric power supplies solves the above restriction and enables the motor to be driven more flexibly. This ensures a favorable drive of the moving object that effectively utilizes the advantages of the two different power sources, that is, the motor and the heat engine. Since the moving object has the secondary battery, the kinetic energy of the moving object through the regenerative braking can be recovered in the form of electric power. These functions enable the second moving object of the present invention to attain a drive of excellent fuel consumption and environmental properties. The heat engine here includes a diversity of engines that output power by taking advantage of heat, such as internal combustion engines and external combustion engines. The term xe2x80x98powerxe2x80x99 used in the specification hereof is not restricted to the power that is directly used to drive the moving object. The xe2x80x98powerxe2x80x99 here includes the power output from the heat engine for the purpose of power generation.
In the second moving object of the present invention, a variety of settings may be applicable for the selective use of the electric power supplies and the power sources according to the driving state of the moving object.
For example, the second moving object may further include a remaining charge measurement unit that measures a remaining charge of the secondary battery. In this structure, the control unit drives the motor with the secondary battery as a working electric power supply in the case where the observed remaining charge is not less than a predetermined level, while the moving object is in a specific driving state that has been set in advance to select the motor as a working power source.
In the second moving object of this arrangement, when the observed remaining charge of the secondary battery is not less than a predetermined level, the motor is driven with the secondary battery as the working electric power supply. As described previously, the secondary battery recovers the level of electric power by charging. In order to recover the kinetic energy of the moving object through the regenerative braking, it is desirable that the charge level of the secondary battery has some margin to a full charge level. The preferential use of the secondary battery having a sufficient remaining charge effectively draws the advantages of the secondary battery discussed above.
In the second moving object, when the observed remaining charge of the secondary battery is less than the predetermined level, the heat engine may be used as the working power source.
It is also preferable that the control unit drives the motor with the fuel cell as the working electric power supply in the case where the observed remaining charge is less than the predetermined level.
This control procedure enables the motor to be driven as the working power source, even when the secondary battery has an insufficient remaining charge. This arrangement ensures the flexible use of the motor in a wider driving area. The motor is the power source having the better environmental properties than the heat engine. The fuel cells are the electric power supply having the excellent environmental properties. The second moving object of the above application uses the fuel cells when the secondary battery has a relatively low remaining charge. This arrangement desirably saves the fuel for the fuel cells and attains a favorable drive having excellent environmental properties. This control procedure is substantially equivalent to the control that gives a preference to the secondary battery over the fuel cells as the working electric power supply.
The predetermined level as the criterion for the selective use of the electric power supplies is adequately set in a specific range that enables the moving object to be smoothly and efficiently driven, based on the power generation ability of the fuel cells, the load of the fuel for the fuel cells, and the remaining charge of the secondary battery.
In one exemplified structure, the control unit causes an insufficiency of electric power to be compensated with electric power output from the secondary battery in a transient period before the fuel cell ensures a sufficient supply of electric power required to drive the motor, while the fuel cell is selected as a working electric power supply. In this case, the predetermined level is a certain remaining quantity set based on a quantity of electric power that enables the compensation.
The fuel cells generally have a time lag between the activation of the fuel cells and the actual supply of a desired electric power. The above control procedure enables the secondary battery to compensate for an insufficiency of electric power in the transient period before the fuel cells generate a desired electric power. The setting of the predetermined level switches the working electric power supply from the secondary battery to the fuel cells, while the secondary battery still has a remaining quantity of electric power to attain the compensation. This arrangement ensures the compensation of electric power and smoothly switches the working electric power supply without any extreme variation in electric power.
In the second moving object of the present invention, a variety of settings may be applied for the proper selection of the power sources.
In accordance with one preferable application, the second moving object further includes a high torque condition decision unit that determines whether or not the moving object is in a specific driving state that satisfies a preset condition for requiring a high torque. The control unit drives both the heat engine and the motor as working power sources when it is determined that the moving object is in the specific driving state that satisfies the preset condition for requiring a high torque.
This arrangement enables the combined use of the two power sources, so as to output an extremely high torque.
A variety of settings are also applicable for the preset condition.
In one exemplified structure, the moving object further includes an accelerator travel measurement unit that measures an accelerator travel. In this structure, the preset condition is that a variation in accelerator travel is not less than a predetermined value.
In this structure, when the driver abruptly steps on an accelerator pedal for abrupt acceleration, it is determined that a high torque is required.
In another exemplified structure, the moving object further includes a required torque input unit that inputs a required torque. In this structure, the preset condition is that the required torque is not less than a predetermined value.
The required torque may be input directly or set based on the accelerator travel and the vehicle speed. In this structure, when the step-on amount of the accelerator pedal has a large absolute value, for example, in the case of a drive on an upward slope, it is determined that a high torque is required.
In still another exemplified structure, the moving object further includes a drive mode switch that allows a driver of the moving object to select a specific drive mode for requiring a high torque, and the high torque condition decision unit carries out the determination, based on an operating condition of the drive mode switch.
This arrangement enables output of a high torque according to an operation of the driver, thereby improving the facility of the moving object.
The drive mode switch may be a special switch exclusively used for the selection of the drive mode or alternatively a combination switch having other functions as well as the selection of the drive mode. In one typical structure, the power of the heat engine and the motor is output via an automatic transmission. The automatic transmission varies a change gear ratio according to a predetermined map, based on the vehicle speed or another parameter. In the moving object of this structure, the switch used for selecting a change speed mode of the automatic transmission may also be used as the switch for selecting the drive mode. For example, when a specific change speed mode, which uses a speed having a greater change gear ratio than the expected change gear ratio from the vehicle speed, is selected through an operation of the switch, it may be determined that a high torque is required. In another example, when the automatic change speed mode is cancelled and a manual change speed mode is set, it may be determined that a high torque is required.
A variety of settings are applicable for the proper selection of the electric power supplies to drive the motor when a high torque is required.
In accordance with one preferable application, the second moving object further includes a remaining charge measurement unit that measures a remaining charge of the secondary battery, wherein the control unit drives the motor with the secondary battery as a working electric power supply in the case where the observed remaining charge is not less than a predetermined level.
In this application, it is further preferable that the control unit drives the motor with the fuel cell as the working electric power supply in the case where the observed remaining charge is less than the predetermined level.
Namely it is desirable to use the secondary battery preferentially over the fuel cells. As discussed above, this arrangement ensures a selective use of the two electric power supplies by taking the respective advantages of the fuel cells and the secondary battery. An adequate value may be set to the predetermined level according to the remaining charge of the secondary battery or another parameter as described previously.
In accordance with one preferable application of the present invention, the second moving object further includes: a second motor that is driven with the fuel cell and the secondary battery as the electric power supplies; a regulation unit that regulates supplies of electric power respectively fed from the fuel cell and the secondary battery to the second motor; and auxiliary machinery that is linked with the heat engine and the second motor, wherein the control unit drives the second motor while the heat engine is at a stop.
The auxiliary machinery here includes a variety of devices and apparatuses that do not directly participate in output of the power for a drive but are required to be driven during a drive of the moving object, for example, an air conditioner and a power steering. The auxiliary machinery is generally required to be driven irrespective of the type of the working power source currently used for a drive. The second moving object of the above structure has the second motor in addition to the heat engine as the power source that can drive the auxiliary machinery. While the heat engine is at a stop, the auxiliary machinery is driven with the second motor. This arrangement enables the moving object to be smoothly driven.
A variety of settings are applicable for the proper selection of the electric power supplies of the second motor to drive the auxiliary machinery.
In accordance with one preferable application, the second moving object further includes a remaining charge measurement unit that measures a remaining charge of the secondary battery, wherein the control unit drives the second motor with the secondary battery as a working electric power supply in the case where the observed remaining charge is not less than a predetermined level.
In this application, it is further preferable that the control unit drives the second motor with the fuel cell as the working electric power supply in the case where the observed remaining charge is less than the predetermined level.
Namely it is desirable to use the secondary battery preferentially over the fuel cells. As discussed above, this arrangement ensures a selective use of the two electric power supplies by taking the respective advantages of the fuel cells and the secondary battery. An adequate value may be set to the predetermined level according to the remaining charge of the secondary battery or another parameter as described previously.
In the second moving object of the present invention, the power of the motor and the heat engine may be output to a common drive shaft, or may alternatively be output to different drive shafts. In the case where the moving object is a vehicle, the linkage of the motor and the heat engine with different drive shafts actualizes a four-wheel drive vehicle. In this case, the motor may further be connected to the drive shaft, with which the heat engine is linked.
In the structure of four-wheel drive, a variety of settings are applicable for the proper selection of the electric power supplies to drive the motor.
In accordance with one preferable application, the second moving object further includes a remaining charge measurement unit that measures a remaining charge of the secondary battery, wherein the control unit drives the motor with the secondary battery as a working electric power supply in the case where the observed remaining charge is not less than a predetermined level.
It is further preferable that the control unit drives the motor with the fuel cell as the working electric power supply in the case where the observed remaining charge is less than the predetermined level.
Namely it is desirable to use the secondary battery preferentially over the fuel cells. As discussed above, this arrangement ensures a selective use of the two electric power supplies by taking the respective advantages of the fuel cells and the secondary battery. An adequate value may be set to the predetermined level according to the remaining charge of the secondary battery or another parameter as described previously.
The variety of control procedures described above ensure the proper use of the fuel cells and the secondary battery. For example, the fuel cells are driven when the secondary battery has a relatively low remaining charge. The fuel cells generally have a time lag between the activation of the fuel cells and the actual output of a desired electric power. It is accordingly preferable that the second moving object of the present invention has a compensation unit that compensates for the time lag.
For the purpose of compensation, the secondary battery may be used to supplement the electric power before the fuel cells are ready for output of a sufficient electric power as discussed previously.
In accordance with another possible application for the purpose of compensation, the control unit activates the fuel cell, so as to cause the fuel cell to output a preset electric power, even when it is not required to supply electric power from the fuel cell to the motor.
This control operation may, however, lead to waste of the fuel for the fuel cells.
It is accordingly preferable that the second moving object further includes a power estimation decision unit that determines whether or not the moving object is in a specific driving state that satisfies a preset condition, in which there is a little possibility of requirement of an increase in total power to be output from the power sources. The control unit reduces the preset electric power when it is determined that the moving object is in the specific driving state that satisfies the preset condition.
The time lag of the fuel cells has significant effects when it is required to drive the motor with the electric power output from the fuel cells. When the moving object is in a specific driving state that does not require output of the power, for example, when the moving object is at a stop or being braked, it is not highly required to quickly drive the motor. Namely there is a relatively little possibility of issuing a requirement of power generation to the fuel cells. When it is determined that there is a little possibility of issuing a requirement of power generation to the fuel cells, the second moving object of this application reduces the electric power output from the fuel cells. This effectively prevents the fuel for the fuel cells from being wasted. One embodiment of the reducing the electric power fully stops the operation of the fuel cells.
A variety of settings are applicable for the preset condition, in which there is a little possibility of issuing a requirement of power generation.
In accordance with one preferable embodiment, the second moving object further includes: a transmission that changes speed of power output from a working power source according to the driving state of the moving object and outputs the converted power to a drive shaft; and an operation unit that specifies a working condition of the transmission. In this embodiment, the preset condition is that the working condition of the transmission is set to a non-driving state by the operation unit.
A neutral mode in which no power transmission is carried out or a specific mode that is used when the moving object is at a stop corresponds to the non-driving state of the transmission.
In accordance with another preferable embodiment, the second moving object further includes a braking decision unit that determines whether or not the moving object is in the course of braking. In this embodiment, the preset condition is that the moving object is being braked.
The determination for the braking may be performed, based on a variation in vehicle speed, a step-on condition of the brake pedal, or a set of the accelerator pedal to the full-close state.
In accordance with still another preferable embodiment, the second moving object further includes an information receiving unit that receives information regarding whether or not a pathway, on which the moving object runs, is in a jam. In this embodiment, the preset condition is that the pathway is in a jam.
A variety of other settings may also be applied for the preset condition.
As described previously, one preferable application of the present invention is a moving object that properly uses two different electric power supplies, that is, fuel cells and a secondary battery, and two different power sources, that is, a motor and a heat engine. The principle of the present invention is, however, not restricted to this application. The principle of the present invention may also be applied to a moving object that adequately controls the power source with using only the fuel cells as the electric power source.
The present invention is accordingly directed to a third moving object having a motor and a heat engine as power sources to output power to a drive shaft. The third moving object includes: a transmission that varies a change gear ratio in the process of transmitting power output from at least the heat engine to the drive shaft; a fuel cell that feeds a supply of electric power to the motor; and a control unit that controls operations of the fuel cell, the power sources, and the transmission according to a driving state of the moving object.
The third moving object of the present invention has two power sources and one electric power supply, and includes a transmission that varies a change gear ratio in the process of transmitting power output from the power source. The third moving object properly uses the motor and the heat engine, while controlling the transmission. This actualizes a favorable control operation that takes the respective advantages of the motor and the heat engine. Among the variety of applications discussed above with regard to the second moving object of the present invention, the arrangements involved in the proper use of the power sources and the control of the driving state of the fuel cells are also applicable to the third moving object. The following describes some preferable arrangements applied for the control operation.
In accordance with one preferable application, the third moving object further includes a high torque condition decision unit that determines whether or not the moving object is in a specific driving state that satisfies a preset condition for requiring a high torque. In this application, the control unit drives both the heat engine and the motor as working power sources when it is determined that the moving object is in the specific driving state that satisfies the preset condition for requiring a high torque.
In accordance with another preferable application, the third moving object further includes a drive mode switch that allows a driver of the moving object to select a specific drive mode for requiring a high torque. In this application, the control unit drives both the heat engine and the motor as working power sources when the drive mode switch is in a predetermined state.
In accordance with still another preferable application, the control unit activates the fuel cell, so as to cause the fuel cell to output a preset electric power, even when it is not required to supply electric power from the fuel cell to the motor.
In the above application, it is preferable that the third moving object further includes a power estimation decision unit that determines whether or not the moving object is in a specific driving state that satisfies a preset condition, in which there is a little possibility of requirement of an increase in total power to be output from the power sources. The control unit reduces the preset electric power when it is determined that the moving object is in the specific driving state that satisfies the preset condition.
A variety of settings are applicable for the preset condition.
For example, when the third moving object further includes
an operation unit that specifies a working condition of the transmission, the preset condition is that the working condition of the transmission is set to a non-driving state by the operation unit.
In another example, when the third moving object further includes a braking decision unit that determines whether or not the moving object is in the course of braking, the preset condition is that the moving object is being braked.
In still another example, when the third moving object further includes an information receiving unit that receives information regarding whether or not a pathway, on which the moving object runs, is in a jam, the preset condition is that the pathway is in a jam.
Like the second moving object of the present invention discussed above, these applications ensure the proper use of the power sources and the adequate control of the driving state of the fuel cells.
In the moving object having the two electric power supplies, that is, the fuel cells and the secondary battery, and the two power sources, that is, the motor and the heat engine, the heat engine may be utilized as the power source to generate electric power as discussed below.
The present invention is accordingly directed to a fourth moving object that further includes a generator that is used as another electric power supply of the motor and converts power output from the heat engine to electric power, in addition to the basic constituents of the second moving object. In the fourth moving object, the control unit has: a driving state decision unit that determines whether or not the moving object is in a specific driving state that requires the fuel cell to start power generation; and an electric power compensation unit that causes the electric power supplies other than the fuel cell to compensate for the fuel cell and output a required electric power in a period before the fuel cell is ready for power generation, when it is determined that the driving state of the moving object requires the fuel cell to start power generation. The electric power compensation unit includes: an electric power estimation unit that estimates an amount of electric power to be compensated in the period before the fuel cell is ready for power generation; a remaining charge measurement unit that measures a remaining charge of the secondary battery; a secondary battery capacity determination unit that determines whether or not the secondary battery has a sufficient capacity of enabling output of the estimated amount of electric power, based on the observed remaining charge; and a heat engine control unit that drives the heat engine and causes the generator to carry out power generation when it is determined that the secondary battery does not have the sufficient capacity of enabling output of the estimated amount of electric power.
As described previously, the fuel cells often have a time lag between the issuance of a requirement of power generation and the actual supply of sufficient electric power. The arrangement of the fourth moving object properly uses the secondary battery and the generator linked with the heat engine, so as to enable the required electric power to be output in a stable manner. In this case, the electric power of the secondary battery is used preferentially over the generator. Namely the control procedure drives the heat engine only when the secondary battery does not have sufficient electric power. The fourth moving object of this arrangement accordingly has the improved fuel consumption and environmental properties.
In the fourth moving object that utilizes the power of the heat engine for generation of electric power, a variety of structures may be applicable for the combined use of the power of the heat engine for both a drive and power generation. It is, however, preferable that the heat engine outputs power only to drive the generator. In this application, the heat engine is regarded as an auxiliary power source used before the fuel cells are ready for power generation. This effectively reduces the required capacity of the heat engine, thereby reducing the size of the whole power system and improving the fuel consumption and the environmental properties.
The delayed response of the fuel cells for the actual power generation may be compensated with the secondary battery and the generator.
In accordance with one preferable application, the fourth moving object further includes: a temperature measurement unit that measures temperature of the fuel cell; and a cold-time control unit that causes the electric power compensation unit to function effectively at a cold time, when the observed temperature of the fuel cell is not higher than a predetermined value.
The delayed response of the fuel cells is especially significant at the cold time. This arrangement thus desirably cancels the effects due to the delayed response. In this case, it is preferable that the control procedure issues a requirement of power generation to the fuel cells, while the secondary battery has a sufficient level of electric power that can compensate for the delayed response of the fuel cells at an ordinary time except the cold time. This arrangement causes only the secondary battery to be used to compensate for the delayed response at the ordinary time, whereas causing both the secondary battery and the generator to be used to compensate for the delayed response at the cold time. If the control procedure issues a requirement of power generation to the fuel cells only when the secondary battery has a charge level that can compensate for the delayed response at any time including the cold time, the secondary battery should have an extremely high level of remaining charge, which is used as the criterion to determine the issuance of the requirement of power generation. This does not allow the effective use of the secondary battery. The control procedure applied in this arrangement, on the other hand, uses both the secondary battery and the generator at the cold time when an especially long time is required before the fuel cells are ready for power generation. This favorably lowers the required level of remaining charge used as the criterion of the issuance and thereby allows the effective use of the secondary battery.
In the case where the delayed response of the fuel cells is compensated with the electric power converted from the power of the heat engine, the heat engine should be driven to an extent that at least compensates for an insufficiency of electric power output from the secondary battery. It is, however, preferable that the heat engine is driven in a specific driving state, which gives a preference to a driving efficiency, from the viewpoints of the improved fuel consumption and environmental properties. Setting the driving state with the preference to the driving efficiency may result in outputting a greater amount of power that exceeds a required amount to compensate for the insufficient electric power of the secondary battery. In this case, the excess electric power is accumulated in the secondary battery. When the charging of the secondary battery causes the remaining charge of the secondary battery to rise to a level that can compensate for the delayed response of the fuel cells, the preferable control procedure stops operation of the heat engine at that time.
The present invention is further directed to a hybrid system having a plurality of energy output sources, which include at least a fuel cell and a heat engine, and an energy transmission unit that causes energy of the energy output sources to be output to outside in a usable form. The hybrid system further includes: a required energy setting unit that sets a total required energy to be output; a target driving state setting unit that sets respective target driving states of the fuel cell, the heat engine, and the energy transmission unit, while the fuel cell is preferentially used to output the total required energy; a decision unit that determines whether or not a preset condition regarding a working state of the hybrid system is fulfilled; a state change unit that, when it is determined that the preset condition is fulfilled, changes the target driving state of at least one of the fuel cell, the heat engine, and the energy transmission unit to a predetermined state according to the preset condition; and a drive control unit that controls the plurality of energy output sources including at least the fuel cell and the heat engine as well as the energy transmission unit to meet the respective target driving states.
The hybrid system of the present invention has the fuel cells and the heat engine as the energy output sources. The energy output source outputs energy in a variety of forms including mechanical energy and electrical energy. The fuel cells correspond to the energy output source that outputs electrical energy, whereas the heat engine corresponds to the energy output source that outputs mechanical energy. The energy transmission unit included in the hybrid system should be adaptable to the form of energy output from each energy output source and the form of energy supplied to the outside. A conductive line and a receptacle are examples of the means that transmits and outputs electrical energy. A transmission mechanism, such as a gear, and a drive shaft are examples of the means that transmits and outputs mechanical energy. The energy transmission unit also includes a device that converts the form of energy output from each energy output source. In the case where only the mechanical energy is to be supplied to the outside, the energy transmission unit includes a motor that converts electrical energy output from the energy output source into mechanical energy. In the case where only the electrical energy is to be supplied to the outside, on the other hand, the energy transmission unit includes a generator that generates electricity with the mechanical energy output from the energy output source.
The hybrid system of the present invention gives the preference to the fuel cells in the ordinary working state. The expression of xe2x80x98giving the preference to the fuel cellsxe2x80x99 here means that the fuel cells are used preferentially over the heat engine when the working energy output source used to output the required total energy is selectable between the fuel cells and the heat engine. For example, when the use of either one of the fuel cells and the heat engine is sufficient for the energy output, the fuel cells should be used preferentially. In this case, the heat engine is used when the fuel cells can not output a sufficient quantity of energy. The expression of xe2x80x98giving the preference to the fuel cellsxe2x80x99 also means that the fuel cells have a higher ratio of energy output than that of the other energy output source. The fuel cells generate electric power at a high efficiency and have excellent environmental properties without any harmful emission. The hybrid system of the present invention uses the fuel cells preferentially over the heat engine, so as to improve the working efficiency and the environmental properties. The term xe2x80x98workingxe2x80x99 is not restricted to the state of a movement of the hybrid system, for example, a drive or a flight, but also includes the state of outputting some energy in a usable form from the hybrid system that is even at a stop.
As described above, in the hybrid system of the present invention, the fuel cells are basically used in a preferential manner. When the preset condition is fulfilled, however, the state change unit changes the driving state of at least one of the respective constituents, that is, the energy output sources and the energy transmission unit. The changed driving state is determined according to the preset condition. The preset condition regards the working state of the hybrid system. For example, when a specific drive mode is selected or when a constituent of the hybrid system is in a specific driving state, it is determined that the preset condition is fulfilled. The preferential use of the fuel cells basically attains an operation of the hybrid system having the excellent working efficiency and favorable environmental properties. In part of various working conditions, however, such selective use of the energy output sources may be unsuitable. For example, in some cases, the operation of the fuel cells is not desirable even if the working efficiency and the environmental properties are sacrificed. In other cases, the use of the fuel cells does not sufficiently improve the driving efficiency. The hybrid system of the present invention changes the driving state of each constituent under the preset condition, so as to attain the most suitable operation of the constituent.
The following describes the significance of the control carried out in the hybrid system of the present invention. The secondary battery can recover the energy level by charging even during a run of the hybrid system. The fuel cells are, on the other hand, the energy output source of irreversible characteristics and can not recover the energy level unless the FC fuel (the fuel for the fuel cells) is externally supplied once the FC fuel has been used up. Because of such characteristics of the fuel cells, there is accordingly no guarantee that the preferential use of the fuel cells improves the working efficiency and the environmental properties of the hybrid system. The quick consumption of the FC fuel causes the energy output source of a relatively low efficiency, such as the heat engine, to be forcibly used for the subsequent operation. This may lower the mean driving efficiency.
The inventors of the present invention have studied a variety of working conditions of the hybrid system with the plurality of energy output sources including the fuel cells and the heat engine, as well as the frequencies of the respective working conditions. There are a number of optional states in the use of the energy output sources, for example, xe2x80x98the state of preferentially using the fuel cellsxe2x80x99, xe2x80x98the state of minimizing the use of the fuel cells in order to save the FC fuelxe2x80x99, and xe2x80x98the state of equally using the fuel cells and the heat enginexe2x80x99. Based on the results of the study, the inventors have found that the state of preferentially using the fuel cells well contributes to the improvement in driving efficiency and environmental properties and completed the invention. The inventors have also found that under a specific condition, a change of the target driving state of each constituent to a predetermined state corresponding to the specific condition enables the adequate operation of the hybrid system. The control carried out in the hybrid system of the present invention attains a desired operation by taking into account the characteristics of the fuel cells and the frequency of use of the fuel cells in the hybrid system.
In the hybrid system, the operation of each constituent is generally controlled by taking into account the energy per unit time. The term xe2x80x98energyxe2x80x99 used in the description hereof means the energy per unit time, unless otherwise specified. In the description hereof, the term xe2x80x98energyxe2x80x99 is synonymous, in principle, with the terms xe2x80x98powerxe2x80x99 and xe2x80x98electric powerxe2x80x99.
In the hybrid system of the present invention, a variety of settings are applicable for the preset condition and the change of the target driving state of each constituent corresponding to the preset condition.
In accordance with one preferable embodiment, the hybrid system further includes a drive mode switch that is operated by a driver to specify a desired drive mode. In this embodiment, the preset condition, whose fulfillment is determined by the decision unit, is an operating state of the drive mode switch.
This arrangement enables the driver to arbitrarily set the driving state of each constituent, such as the fuel cells or the heat engine, by a simple operation of the drive mode switch. This improves the facility of the hybrid system.
In one embodiment of the hybrid system that enables specification of the desired drive mode through operation of the drive mode switch, the energy is electrical energy, and the preset condition is that a predetermined drive mode, which allows output of electrical energy to outside, is specified through an operation of the drive mode switch. The change carried out by the state change unit represents prohibition of a drive of the heat engine.
The hybrid system of this arrangement enables electrical energy to be supplied to the outside. The hybrid system of this arrangement includes a generator that converts the mechanical energy of the heat engine into electrical energy and a receptacle that causes the electrical energy output from the heat engine and the fuel cells to be supplied to the outside, as the energy transmission unit. The receptacle enables the use of various electric appliances in the field, for example, at a destination of the hybrid system. This improves the facility of the hybrid system.
The hybrid system of the present invention preferentially uses the fuel cells in the ordinary drive mode and drives the heat engine when the output of the fuel cells does not meet the required level. In the hybrid system of the above structure, the drive of the heat engine is forbidden in the predetermined drive mode that allows a supply of electric power, for example, through the receptacle. In many cases, the use of the electric power in the field is a requirement of low priority. The continuous allowance of the operation of the heat engine under such conditions causes the heat engine to be activated at the time of supply of electric power. This undesirably damages the driving efficiency and the environmental properties of the hybrid system. The heat engine generally has a large working noise and may impair the quietness in the field. The hybrid system of the above arrangement forbids the operation of the heat engine in the predetermined drive mode that allows the external use of electrical energy, so as to avoid these potential problems.
In the application that forbids operation of the heat engine, it is preferable that the hybrid system further includes a starter switch that is operated by the driver to direct a start of the heat engine. The preset condition is that the start of the heat engine is directed through an operation of the starter switch, while the predetermined drive mode is specified, and the change carried out by the state change unit represents the start of the heat engine.
When it is highly required to supply electric power in the field, this arrangement enables the driver to intentionally start the heat engine through operation of the starter switch, so as to ensure a further supply of electric power. This improves the facility of the hybrid system. The description above regards only the operations of the fuel cells and the heat engine, but this does not mean to exclude the hybrid system having other energy output sources.
In another embodiment of the hybrid system that enables specification of the desired drive mode through operation of the drive mode switch, the energy is mechanical energy, and the preset condition is that a predetermined drive mode, in which either one of the fuel cell and the heat engine is selected and used as a working energy output source, is specified through an operation of the drive mode switch. The change carried out by the state change unit represents execution of a drive of the working energy output source and prohibition of a drive of the other energy output source, which is other than the working energy output source.
The hybrid system of this arrangement enables mechanical energy to be supplied to the outside. The hybrid system of this arrangement includes a motor that converts the electrical energy of the fuel cells into mechanical energy and a drive shaft that causes the mechanical energy output from the heat engine and the fuel cells to be supplied to the outside, as the energy transmission unit. Application of the output power for a drive enables the hybrid system to be driven with either one of the fuel cells and the heat engine.
The hybrid system of the present invention preferentially uses the fuel cells in the ordinary drive mode and drives the heat engine when the output of the fuel cells does not meet the required level. The hybrid system of the above structure enables the driver to arbitrarily select a desired power source. For example, when it is required to use the electric power output from the fuel cells in the field, the driver selects the drive mode that uses the heat engine. Such selection desirably reduces the consumption of the FC fuel before the hybrid system arrives at the field. This ensures the effective use of the fuel cells in the field. In another example, the energy output sources are selectively used according to the requirement with regard to the response of the hybrid system. The fuel cells generally have a poor output response. Selection of the drive mode using the heat engine enables a drive of the hybrid system with a good response. In still another example, the energy output sources are selectively used according to the requirement of noise reduction. The heat engine generally has a large working noise. When noise reduction is highly required, for example, during a drive at midnight, selection of the drive mode using the fuel cells ensures a drive in stillness. The arrangement of enabling the driver to arbitrarily select the desired power source improves the facility of the hybrid system.
In the application that forbids operation of the other energy output source, the hybrid system further includes a starter switch that is operated by the driver to direct a start of the other energy output source. The preset condition is that the start of the other energy output source is directed through an operation of the starter switch, while the predetermined drive mode is specified, and the change carried out by the state change unit represents the start of the other energy output source.
This arrangement enables the other energy output source to be activated according to the requirements. The operation of the energy output sources according to the requirement of power output desirably improves the facility of the hybrid system. The description above regards only the operations of the fuel cells and the heat engine, but this does not mean to exclude the hybrid system including other energy output sources.
In still another embodiment of the hybrid system that enables specification of the desired drive mode through operation of the drive mode switch, the energy is mechanical energy, and the preset condition is that a predetermined drive mode, in which only the fuel cell is selected and used as a working energy output source, is specified through an operation of the drive mode switch. The change carried out by the state change unit represents execution of a drive of the fuel cell and prohibition of warm-up of the heat engine.
The structure of enabling the driver to select the working energy output source through the operation of the drive mode switch has the advantages discussed previously. In this embodiment, when the predetermined drive mode, in which only the fuel cells are used as the working energy output source, is selected, the control procedure forbids not only a drive but even warm-up or preparation for a drive of the heat engine. The prohibition of even the warm-up of the heat engine further improves the fuel consumption and the environmental properties of the hybrid system.
The prohibition of the warm-up of the heat engine naturally leads to a little response delay when the energy output from the heat engine is required. The driver, however, intentionally selects the drive mode, in which only the fuel cells are used as the working energy output source, so that the response delay does not have significant effects on the good drive feeling of the driver. The drive mode is generally set to prevent a significant variation in drive feeling. The arrangement of this embodiment, on the other hand, enables the driver to intentionally select the desired drive mode with the comprehension of the characteristics thereof. The drive mode is set free from the restriction of substantially constant drive feeling but by placing the importance specifically on the improvement in fuel consumption and environmental properties.
Such control operation is on the premise that the fuel cells are in a workable state. Even when the predetermined drive mode, in which only the fuel cells are used as the working energy output source, is selected, if the fuel cells are not in the workable state, the drive of the heat engine should be allowed automatically or manually.
In accordance with another preferable embodiment that varies the settings for the preset condition and the change of the target driving state of each constituent corresponding to the preset condition, the hybrid system further includes a detector that detects a power generation capacity of the fuel cell. In this embodiment, the preset condition is that the power generation capacity is lowered to or below a predetermined level, and the change carried out by the state change unit represents a reduction of output of the fuel cell.
In this embodiment, the power generation capacity may be observed with a variety of parameters.
For example, the detector detects the power generation capacity, based on a remaining quantity of a fuel for the fuel cell.
In another example, the detector detects the power generation capacity, based on temperature of the fuel cell.
In the case where the power generation capacity is detected according to the remaining quantity of the FC fuel, a decrease in remaining quantity of the FC fuel leads to a decrease in power generation capacity. In the case of the decrease in remaining quantity of the FC fuel, the hybrid system of the above arrangement reduces the output of the fuel cells, thereby preventing the FC fuel from being excessively consumed. As mentioned previously, the fuel cells are the irreversible energy output source and are not usable once the FC fuel has been used up. The hybrid system of the above arrangement reduces the consumption of the FC fuel and thereby enables the fuel cells to be kept in the workable state over a long time period. The fuel cells can thus be driven in a driving state of higher effectiveness.
In the case where the power generation capacity is detected according to the temperature of the fuel cells, the power generation capacity decreases when the temperature of the fuel cells rises to an abnormally high level or when the fuel cells are not sufficiently warmed up to a certain temperature level to be ready for power generation. The requirement of the high power output from the fuel cells under such conditions may significantly shorten the life of the fuel cells or cause other damages on the fuel cells. The arrangement of the above embodiment reduces the output of the fuel cells, thereby avoiding such potential damages.
In the hybrid system that reduces the output of the fuel cell according to the observed power generation capacity, the change carried out by the state change unit may represent an increase in output of the heat engine.
This application compensates for the effects due to the lowered output of the fuel cells and enables the output of the required total energy.
In accordance with another application of the hybrid system that reduces the output of the fuel cell according to the observed power generation capacity, the energy is rotational energy of a rotating shaft, and the energy transmission unit has a speed change gear unit that switches a change gear ratio between at least two different stages. The speed change gear unit changes the speed of the rotational energy output from each of the energy output sources at a preset change gear ratio and outputs the converted rotational energy. In this application, the change carried out by the state change unit represents an increase in change gear ratio set in the speed change gear unit.
In the case of the rotational energy, the lowered output of the fuel cells may cause a significant decrease in output torque. This arrangement sets the greater change gear ratio, so as to control the decrease in output torque.
In accordance with still another preferable embodiment that varies the settings for the preset condition and the change of the target driving state of each constituent corresponding to the preset condition, the hybrid system further includes a temperature measurement unit that measures temperature of the heat engine. In this embodiment, the preset condition is that the observed temperature of the heat engine is not higher than a predetermined level, and the change carried out by the state change unit represents execution of warm-up of the heat engine.
The sufficient warm-up is desired for the improved driving efficiency and the better exhaust emission control of the heat engine. In the hybrid system of the present invention, while the fuel cells are used as the working energy output source, the temperature of the heat engine might be lowered. The hybrid system of this embodiment warms up the heat engine against the temperature decrease thereof. This improves the driving efficiency and the exhaust emission control properties of the heat engine when the power output from the heat engine is required. An additional condition may be set for the execution of the warm-up of the heat engine. This modified control procedure warms the heat engine up only when it is determined that there is a good possibility of requirement of the power output from the heat engine. This effectively saves the fuel required for the warm-up operation and further improves the driving efficiency of the heat engine.
In accordance with another preferable embodiment that varies the settings for the preset condition and the change of the target driving state of each constituent corresponding to the preset condition, the hybrid system further includes: a temperature measurement unit that measures temperature of the heat engine; and a heat supply unit that feeds at least part of thermal energy generated by the fuel cell to the heat engine. In this embodiment, the preset condition is that the observed temperature of the heat engine is not higher than a predetermined level, and the change carried out by the state change unit represents an increase in output of the fuel cell.
The heat supply unit may have any arbitrary structure. For example, a common cooling mechanism of the fuel cells and the heat engine may be utilized as the heat supply unit.
The hybrid system of this embodiment implements the warm-up of the heat engine by utilizing the heat generated by the fuel cells. This arrangement does not independently warm the heat engine up and thereby saves the fuel required for the warm-up operation. In this arrangement, the heat engine may also be warmed up only when it is determined that there is a good possibility of requirement of the power output from the heat engine. This modified control procedure further improves the driving efficiency of the heat engine.
The present invention is further directed to another hybrid system having a plurality of energy output sources, which include at least a fuel cell and a heat engine, and an energy transmission unit that causes energy of the energy output sources to be output to outside in a usable form. The hybrid system further includes: an energy output source selection switch that is operated by a driver of the hybrid system to select at least one of the energy output sources as a working energy output source; a target driving state setting unit that sets respective target driving states of the fuel cell, the heat engine, and the energy transmission unit according to the selection with the energy output source selection switch; and a drive control unit that controls the plurality of energy output sources including the fuel cell and the heat engine as well as the energy transmission unit to the respective target driving states.
In this hybrid system, the target driving state setting unit may set the target driving state of the heat engine to a specific condition that forbids not only a drive but warm-up of the heat engine, when only the fuel cell is selected as the working energy output source through operation of the energy output source selection switch.
The operation of the energy output source selection switch enables the driver to freely select the working energy output source. For example, when the hybrid system has the fuel cells and the heat engine as the available energy output sources, there are three optional modes: that is, the mode of using only the fuel cells, the mode of using only the heat engine, and the mode of using the both. The hybrid system of the above arrangement enables the driver to freely select a desired mode among these three optional modes. The selective use of the working energy output source improves the facility of the hybrid system. The favorable control procedure forbids not only a drive but even warm-up of the heat engine when only the fuel cells are selected as the working energy output source. This further improves the fuel consumption and the environmental properties of the hybrid system as discussed previously.
The hybrid systems of the various applications discussed above are not restricted to have only the fuel cells and the heat engine.
In accordance with another preferable structure, the hybrid system further includes an accumulator as a reversible energy output source. In this case, the target driving state setting unit sets the respective target driving states by taking into account electrical energy input into and output from the accumulator.
The accumulator is a reversible energy output source that recovers its energy level by charging in the course of a drive of the hybrid system. A secondary battery and a capacitor are typical examples of the accumulator. This hybrid system has the highly efficient but irreversible fuel cells and the reversible accumulator as the available energy output sources that output electrical energy. The combination of the energy output sources having different characteristics desirably improves the working efficiency, the environmental properties, and the facility of the hybrid system by taking the advantages of the respective energy output sources. In the hybrid system of the above application, the accumulator may be used preferentially over the fuel cells or alternatively the fuel cells may be used preferentially over the accumulator. The priority may be set according to the respective rated outputs of the fuel cells and the accumulator and the capacity of the accumulator.
The principle of the present invention is applicable to a diversity of immobilized systems, such as plants and industrial machines, as well as to moving objects. The term xe2x80x98moving objectxe2x80x99 used in the description hereof includes a diversity of moving objects that move with the power, for example, vehicles, ships and vessels, aircraft, airships, and other flying objects. The purpose of the moving object is not restricted to the transportation of people or things nor to the boarding.
The present invention is further directed to still another hybrid system having a plurality of energy output sources, which include at least a fuel cell and a heat engine, and an energy transmission unit that causes energy of the energy output sources to be output to outside in a usable form. The hybrid system further includes a control unit that controls operations of the fuel cell and the heat engine, in order to cause the fuel cell to be used and output energy preferentially, while both the fuel cell and the heat engine are ready for energy output.
This hybrid system preferentially uses the fuel cells over the heat engine, thus significantly improving the working efficiency and the environmental properties like the hybrid systems of various applications described previously. The variety of arrangements discussed above with regard to the other hybrid systems may also be applied for this hybrid system.
The technique of the present invention may be actualized by a hybrid moving object.
The present invention is thus directed to a first hybrid moving object having a plurality of energy output sources, which include at least a fuel cell and a heat engine, and an energy transmission unit that causes energy of the energy output sources to be output to outside in a usable form. The first hybrid moving object further includes: a deterioration detector that detects deterioration of at least either one of the fuel cell and the heat engine; and a deterioration-time control unit that, when deterioration is detected with regard to one of the fuel cell and the heat engine, controls the other of the fuel cell and the heat engine to compensate for an effect on energy output due to the deterioration.
The present invention is also directed to a second hybrid moving object having a plurality of power output sources, which include at least a fuel cell and a heat engine, and a transmission mechanism that transmits power output from the power output sources to a drive shaft via a transmission. The second hybrid moving object further includes: a deterioration detector that detects deterioration of the fuel cell; and a transmission control unit that, when deterioration of the fuel cell is detected, controls the transmission to compensate for an effect on energy output due to the deterioration.
In the event that either one of the fuel cells and the heat engine deteriorates, the first hybrid moving object regulates the output of the other energy output source that does not deteriorate, and thereby compensates for the adverse effects of the deterioration. The deterioration here represents the failure of proper output due to malfunction, shortage of the fuel, or change with the elapse of time. In the first hybrid moving object, the detection of deterioration may be carried out for both or either one of the fuel cells and the heat engine. In the event that the fuel cells deteriorate, the second hybrid moving object controls the transmission and thereby compensates for the adverse effects of the deterioration. The variety of arrangements discussed above with regard to the hybrid systems may also be applied for these hybrid moving objects. The principle of the present invention may also be actualized by a method of controlling the hybrid system.
The present invention is also directed to a fifth moving object having a heat engine as a power source that outputs power to a drive shaft, and a motor that applies a torque to a specific site in order to compensate for a variation in torque output from the heat engine to the drive shaft. The fifth moving object further includes: an accumulator that is charged with electric power and a power generator unit, which are included in an electric power system that transmits electric power to and from the motor; a target torque setting unit that sets a torque to compensate for a variation in torque of the heat engine as a target torque of the motor; and a control unit that selectively uses the accumulator and the power generator unit according to a sign of the target torque, so as to enable the motor to be driven with the target torque.
The fifth moving object of the present invention improves the energy efficiency under the control of restricting the torque variation. The variation in torque output from the heat engine is controlled by regulating the torque of the motor. In the case where the actual torque, which is actually output from the heat engine, is greater than a required torque, the motor applies a negative torque, so as to compensate for the torque variation. In the case where the actual torque is smaller than the required torque, on the contrary, the motor applies a positive torque, so as to compensate for the torque variation. In the fifth moving object, the control technique selectively uses the working electric power system according to the sign of the target torque of the motor. In the case of a negative target torque, the electric power regenerated by the motor is accumulated in the accumulator. In the case of a positive target torque, on the other hand, the electric power is supplied from the power generator unit to enable power operation of the motor. There is no supply of electric power from the accumulator to the motor in the case of the positive target torque. During the power operation of the motor, the electric power is supplied from the power generator unit. This improves the energy efficiency during the power operation of the motor. The supply of electric power from the accumulator is mainly based on the excess power previously output from the heat engine. In this case, there are both the charge loss in the process of charging the accumulator with the excess power and the discharge loss in the process of discharging the accumulator. The supply of electric power from the power generator unit, on the other hand, is not via the charge and discharge processes into and from the accumulator, thereby attaining the high energy efficiency.
The effectiveness of this technique of the fifth moving object is affected by the charge-discharge characteristics of the accumulator. In some cases, the charge and discharge efficiencies of the accumulator show non-linear characteristics according to the amounts of input and output electric power and the charge level. The accumulator that is charged with electric power and is discharged to release electric power through chemical reactions, such as the secondary battery, may have the varying efficiency with a variation in charge-discharge cycle. The torque variation of the heat engine arises at relatively high frequencies. Compensation of the torque variation with the electric power output from the accumulator may cause frequent discharges at the especially low efficiencies. The technique of the fifth moving object, on the other hand, compensates the torque variation with the power generator unit of high efficiency. This arrangement effectively prevents the accumulator from being discharged in the driving state of low discharge efficiency. This enables the electric power output from the accumulator to be used in the driving state of high discharge efficiency and thereby improves the total driving efficiency of the moving object as well as the driving efficiency in the course of controlling the torque variation.
Typical examples of the accumulator include a secondary battery and a capacitor. Typical examples of the power generator unit include fuel cells and a generator. The fuel cells have an advantage of good driving efficiency. The generator may be driven by means of a heat engine. In this case, the preferable control procedure regulates the loading applied from the generator to the heat engine to a fixed value, irrespective of the amount of electric power required for the motor.
The fifth moving object discussed above selectively uses the accumulator and the power generator unit according to the sign of the target torque of the motor that compensates for the torque variation.
The present invention is also directed to a sixth moving object having a heat engine as a power source that outputs power to a drive shaft and a control mechanism that checks a variation in torque output from the heat engine to the drive shaft. The control mechanism includes: a first motor and a second motor that apply a torque to the drive shaft; and an accumulator that is charged with electric power and a power generator unit, which are included in an electric power system that transmits electric power to and from the first and second motors. The control mechanism further includes: a target torque setting unit that respectively sets target torques of the first motor and the second motor, as long as a condition of maintaining a torque to be output to the drive shaft, a condition of compensating for the variation in torque, a condition of making the torque of the first motor not greater than zero, and a condition of making the torque of the second motor not less than zero are fulfilled; and a control unit that regulates electric power transmitted between the first motor and the accumulator and electric power transmitted between the second motor and the power generator unit, so as to enable the first motor and the second motor to be driven with the respective target torques.
The technique of the sixth moving object selectively uses the accumulator and the power generator unit as the working electric power system, as well as the first motor and the second motor according to the magnitude of the torque to be applied to compensate for the torque variation. The arrangement of the sixth moving object also enables the control of the torque variation with a high efficiency, like the arrangement of the fifth moving object.
In accordance with one preferable embodiment that controls the torque variation, the fifth moving object further includes a charge state detector that observes a charge level of the accumulator. The control unit selectively uses the accumulator and the power generator unit according to the observed charge level of the accumulator, so as to drive the motor.
For example, the control unit may carry out the control that properly uses the accumulator and the power generator unit according to the sign of the target torque, only when the observed charge level of the accumulator is not higher than a predetermined level.
This desirably prevents the accumulator from being excessively charged.
Each of the moving objects of the present invention discussed above has a plurality of fuel reservoir units, in which a plurality of fuels are separately stored. The present invention also includes a configuration of a fuel supply mechanism that adequately supplies the plurality of fuels to the respective fuel reservoir units.
The present invention is thus directed to a first fuel supply mechanism, which includes: a fuel supply unit that supplies a plurality of different fuels; a plurality of fuel reservoir units that respectively store the plurality of different fuels therein; and a fuel inlet unit that is connected with the fuel supply unit and leads the supplies of different fuels fed from the fuel supply unit to the plurality of fuel reservoir units. The fuel inlet unit has a plurality of openings that are provided corresponding to the plurality of fuel reservoir units and respectively connect with the corresponding fuel reservoir units. The plurality of openings are formed to have different shapes.
In the first fuel supply mechanism of the present invention, the plurality of openings have different shapes corresponding to the plurality of different fuels. This effectively prevents the user from being mixed up by the plurality of different fuels at the time of fuel supply. Especially preferable is that the respective openings of the fuel inlet unit have the shapes allowing one-to-one connection with the fuel supply unit. This structure more securely prevents the confusion between different fuels.
In accordance with one preferable embodiment of the first fuel supply mechanism, the fuel inlet unit has the plurality of openings that are located close to each other in a predetermined area on an outer wall surface of the moving object. The fuel inlet unit has a single cover member that covers over the plurality of openings.
This arrangement enables all fuel supply operations to be performed in the predetermined area, thereby simplifying the work required for the fuel supply. The single cover member to cover over the plurality of openings desirably reduces the required number of parts involved in the opening and closing mechanism of the cover member and simplifies the structure of the fuel inlet unit.
For the purpose of labor saving at the time of fuel supply, it is desirable that the cover member of the fuel inlet unit is opened by a single action. This is especially preferable when the fuel inlet unit has a plurality of cover members corresponding to the plurality of different fuels.
The plurality of different fuels respectively stored in the plurality of fuel reservoir units may be supplied to all the energy output sources. Alternatively there may be one or plural fuels that are supplied only to part of the energy output sources.
The present invention is also directed to a second fuel supply mechanism, which includes: a plurality of fuel reservoir units that respectively store a plurality of different fuels therein; a plurality of flow paths that are provided corresponding to the plurality of fuel reservoir units and respectively lead external supplies of the plurality of different fuels to the corresponding fuel reservoir units; and a detector that is disposed in at least one flow path among the plurality of flow paths and obtains information regarding a type of fuel passing through the flow path.
In the second fuel supply mechanism, the detector identifies the type of the fuel supplied through the flow path. It is preferable that the second fuel supply mechanism further includes an alarm unit that informs a user of an inappropriate supply of fuel. The alarm unit may provide an alarm display, an alarm sound, or an alarm of any other suitable form.
In accordance with one preferable application, the second fuel supply mechanism further includes: a plurality of energy output sources, each of which receives a supply of one of the plurality of different fuels stored in the plurality of fuel reservoir units and generates energy; and a fuel identification unit that determines whether or not the fuel passing through the flow path is identical with the fuel that is to be stored in the fuel reservoir unit corresponding to the flow path, based on the information obtained by the detector. The second fuel supply mechanism further includes a prohibition unit that forbids generation of energy by the energy output source that receives the supply of fuel from the fuel reservoir unit corresponding to the flow path, when the fuel identification unit determines that the fuel passing through the flow path is different from the fuel that is to be stored in the fuel reservoir unit corresponding to the flow path.
In the event that the wrong fuel is mistakenly fed to the fuel reservoir unit, this arrangement effectively prevents the energy output source from being driven with the fuel. One possible modification drives the energy output source corresponding to another fuel reservoir unit, in which the right fuel is stored, instead of the energy output source subjected to the prohibition. This ensures the required energy even when the wrong fuel is mistakenly supplied.
The fuel supply unit that supplies at least two fuels among the plurality of different fuels has a configuration corresponding to the arrangement of the first fuel supply mechanism.
The fuel supply unit has a joint member that is connected to the moving object and enables the at least two fuels to be supplied to the moving object. The joint member includes a plurality of ejection outlets that are provided independently corresponding to the at least two fuels supplied from the fuel supply unit to the moving object. The plurality of ejection outlets are formed to have different shapes and cause the corresponding fuels to be ejected therefrom.
In the fuel supply unit of this configuration, the plurality of ejection outlets, from which the corresponding fuels are ejected, have different shapes. This effectively prevents the user from being mixed up by the at least two fuels at the time of fuel supply. Especially preferable is that each of the ejection outlets has a shape allowing one-to-one connection with the opening of the fuel inlet unit. This structure more securely prevents the confusion between different fuels. From this point of view, it is preferable that each of the ejection outlets corresponding to a certain fuel has a shape forbidding connection with any openings of the fuel inlet unit except the right opening corresponding to the certain fuel.